单选题：In order to manage a project effectively, work should be bro

In order to manage a project effectively, work should be broken down into small pieces．Which of the following does NOT describe how far each task should be broken down?（　）
A．Can be completed in under 80 hours
B．Can not be logically subdivided further
C．Is done by one person
D．Can be realistically estimated A．可以在80小时以下完成。
B．不能再进一步进行逻辑细分了。
C．可由一个人完成。
D．可以进行实际估算。